SDC1 and Miyoshi myopathy: As shown in Figure 2A, CD138 expression was significantly lower in HD-EVs (CD138 MRFI, median ± SE: 1.85 ± 0.33) compared to MM patients (14.08 ± 4.56, p < 0.0001), including both NDMM (10.01 ± 5.71, p < 0.0001) and RRMM (16.76 ± 6.18, p < 0.0001) subgroups.